1. Field of the Invention
The present invention relates to a power transmission apparatus.
2. Related Art
US2008/0230295 discloses a conventional power transmission apparatus. This power transmission apparatus includes a clutch housing which is concentrically provided on an outer periphery of a hollow input shaft and on which a ring gear and an interrupting clutch are supported. Both ends of the clutch housing are rotatably supported on a case via bearings. The clutch can be operated by a hydraulic piston provided on the case.
The ring gear is in mesh with a pinion gear which is formed on an output shaft of rear wheel side.
Accordingly, if the clutch is operated by driving the hydraulic piston, the clutch housing is connected to the hollow shaft and an input power from the hollow shaft is rotationally transmitted to the pinion gear via the clutch, the clutch housing and the ring gear. Consequently, a power can be outputted from the output shaft to the rear wheels.
However, since the ring gear and the clutch are arranged adjacent to each other between the bearings and supported on the clutch housing in this configuration, the ring gear adjacent to the clutch is subjected to a constraint by the clutch. Accordingly, there is a problem that a limit in reducing a diameter of the ring gear is caused and thus the degree of design freedom is inhibited.
US2009/0229905 discloses another conventional power transmission apparatus. This power transmission apparatus includes an input shaft into which a driving force is inputted, a bevel gear as an input gear which is rotationally driven by the driving force inputted, an output pinion as an output gear which is in mesh with the bevel gear and an output shaft which is provided to rotate integrally with the output pinion.
In this power transmission apparatus, a clutch plate as a clutch device is provided between a clutch hub and a clutch drum which are respectively provided on the input shaft and the bevel gear to rotate integrally therewith and a cam mechanism actuated by a servo motor as an actuator which is operated to interrupt the clutch plate is disposed on the input shaft.
However, in this power transmission apparatus, since the actuator such as the servo motor for interrupting the clutch device or the cam mechanism is arranged around the input shaft, there is a risk of interference with surrounding members such as an engine arranged around the power transmission apparatus. Accordingly, it is difficult to change the design of the actuator in order to improve the interruption property of the clutch device.
On the contrary, JP-A-62-059130 discloses further another power transmission apparatus. This power transmission apparatus includes an input shaft into which a driving force is inputted, a power distributing drive gear as an input gear which is provided to rotate integrally with the input shaft, a power distributing driven gear as an intermediate gear which is in mesh with the power distributing drive gear, an intermediate shaft which is provided to rotate integrally with the power distributing driven gear, an auxiliary shaft which is disposed to rotate relative to the intermediate shaft, a turning drive gear as an intermediate output gear which is provided to rotate integrally with the auxiliary shaft, a turning driven gear which is in mesh with the turning drive gear and an output shaft which is provided to rotate integrally with the turning driven gear.
In this power transmission apparatus, the clutch gears as the clutch device are respectively provided on the intermediate shaft and the auxiliary shaft and a dog clutch as a clutch member is connected to the clutch gear of the intermediate shaft to move in an axial direction and rotate integrally therewith. As the dog clutch is moved in an axial direction, the dog clutch is connected to the clutch gear of the auxiliary shaft. Further, the intermediate shaft and the auxiliary shaft are connected to each other to rotate integrally. In this way, a power transmission between the intermediate shaft and the auxiliary shaft is allowed. This clutch member is moved in an axial direction by an actuator such as a shift fork provided around the intermediate shaft to interrupt the clutch device.
However, in the power transmission apparatus as disclosed in JP-A-62-059130, since the clutch device is provided between the intermediate shaft and the auxiliary shaft and the clutch member is provided in the intermediate shaft to move axially, it is necessary to secure a moving stroke of the clutch member in the intermediate shaft and thus the size of the power transmission apparatus becomes larger.
Further, since the input shaft and the input gear are provided to rotate integrally, the intermediate gear in mesh with the input gear is provided on the intermediate shaft to rotate integrally therewith and the clutch device is provided between the auxiliary shaft and the intermediate shaft, a driving force inputted from the input shaft side causes the intermediate shaft to be normally rotated even in a disconnected state of the clutch device. Accordingly, the fuel consumption is lowered.